American Kennel Club
American Kennel Club: Dachshund Breed Standard
Official site for the American Kennel Club provides basic information for the Dachshund on general appearance, size, proportion, temperament, history, and more.
Wikimedia
Wikipedia: Dachshund
Although Wikipedia is a "free" encyclopedia, it usually has good entries. This entry includes a description and information on temperament, health, and history.